Improve the test

src/test/regress/citus_tests/test/test_maintenancedeamon.py

@@ -5,7 +5,7 @@
 import time
 
 
-def wait_until_deamons_start(deamoncount, cluster):
+def wait_until_maintenance_deamons_start(deamoncount, cluster):
     i = 0
     n = 0
 
@@ -26,13 +26,17 @@ def wait_until_deamons_start(deamoncount, cluster):
 def test_set_maindb(cluster_factory):
     cluster = cluster_factory(0)
 
+    # Test that once citus.main_db is set to a database name
+    # there are two maintenance deamons running upon restart.
+    # One maintenance deamon for the database of the current connection
+    # and one for the citus.main_db.
     cluster.coordinator.create_database("mymaindb")
     cluster.coordinator.configure("citus.main_db='mymaindb'")
     cluster.coordinator.restart()
 
     assert cluster.coordinator.sql_value("SHOW citus.main_db;") == "mymaindb"
 
-    wait_until_deamons_start(2, cluster)
+    wait_until_maintenance_deamons_start(2, cluster)
 
     assert (
         cluster.coordinator.sql_value(
@@ -41,10 +45,32 @@ def test_set_maindb(cluster_factory):
         == 1
     )
 
+    # Test that once citus.main_db is set to empty string
+    # there is only one maintenance deamon for the database
+    # of the current connection.
     cluster.coordinator.configure("citus.main_db=''")
     cluster.coordinator.restart()
     assert cluster.coordinator.sql_value("SHOW citus.main_db;") == ""
 
-    wait_until_deamons_start(1, cluster)
+    wait_until_maintenance_deamons_start(1, cluster)
+
+    # Test that after citus.main_db is dropped. The maintenance
+    # deamon for this database is terminated.
+    cluster.coordinator.configure("citus.main_db='mymaindb'")
+    cluster.coordinator.restart()
+    assert cluster.coordinator.sql_value("SHOW citus.main_db;") == "mymaindb"
+
+    wait_until_maintenance_deamons_start(2, cluster)
+
+    cluster.coordinator.sql("DROP DATABASE mymaindb;")
+
+    wait_until_maintenance_deamons_start(1, cluster)
+
+    assert (
+        cluster.coordinator.sql_value(
+            "SELECT count(*) FROM pg_stat_activity WHERE application_name = 'Citus Maintenance Daemon' AND datname='mymaindb';"
+        )
+        == 0
+    )
 
     cluster.coordinator.cleanup_databases()